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Trial registered on ANZCTR

Registration number

ACTRN12622000497707

Ethics application status

Approved

Date submitted

14/03/2022

Date registered

29/03/2022

Date last updated

3/03/2023

Date data sharing statement initially provided

29/03/2022

Type of registration

Prospectively registered

Titles & IDs

Public title

Gambling Habit Hacker: A micro-randomised trial of planning interventions delivered via a Just-In-Time Adaptive Intervention for adult gamblers.

Scientific title

Gambling Habit Hacker: A micro-randomised trial of planning interventions delivered via a Just-In-Time Adaptive Intervention for adult gamblers.

Secondary ID [1]

Nil

Universal Trial Number (UTN)

U1111-1274-3609

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Problem gambling

Condition category

Condition code

Mental Health

Addiction

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

Gambling Habit Hacker is a Just-In-Time-Adaptive-Intervention which provides in the moment support for adhering to gambling limits. The aim of this implementation planning intervention is to prevent the deterioration of intention and to support in-the-moment selection of behaviour change strategies and the establishment of robust action and coping plans.

Gambling Habit Hacker is informed by the Health Action Process Approach and implementation intentions literature and delivered in accordance with Self-determination Theory. This JITAI employs decision rules specifying that participants who are receptive to treatment (available for treatment) and report low goal strength of intention, low goal self-efficacy, low urge self-efficacy or a high-risk situation (tailoring variables) in Ecological Momentary Assessments (EMAs) sent during three semi-random times a day are delivered action and coping planning activities to implement selected behaviour change strategies. These components are guided primarily by the long-term goal of reducing gambling expenditure (distal outcome), which is posited to be achieved through the short-term goal of adhering to gambling expenditure limits (primary proximal outcome) via increased strength of intention, goal self-efficacy, and urge self-efficacy (secondary proximal outcomes).

Trial design
A micro-randomised trial (MRT), a form of sequential factorial design, will be employed to inform the optimisation of this JITAI. In this MRT, each participant will be randomised to an intervention condition or control condition at each decision point across a 28-day period. The MRT will be supplemented with: (1) a within-group follow-up evaluation to explore the longer-term outcomes of the intervention, in which changes to the primary (gambling expenditure) and secondary (gambling symptom severity, gambling frequency, psychological distress, personal wellbeing, situational confidence, and planning propensity) outcome measures from pre-intervention evaluation to post-intervention and six-month follow-up evaluations; and (2) an evaluation of the usability and acceptability of the JITAI using usability and acceptability items in the post-intervention survey of the within-group follow-up evaluation, indices of app usage and engagement, and qualitative telephone interviews.

EMA features:
All participants will be prompted to complete time-based EMAs (t-EMAs) via push notifications at random times during three pre-specified periods (morning, afternoon, and evening). These in-app t-EMAs will consist of single items assessing strength of intention, goal self-efficacy, urge self-efficacy and presence of a high-risk situation (tailoring variables). The high-risk situations include positive reinforcement high-risk situations (wanting to win back losses), negative reinforcement high-risk situations (temptations to gamble, unpleasant emotions), alcohol or drug consumption, and gambling proximity (whether the person is currently gambling). These items are mostly measured on 5-point Likert scales (from 1-5). The t-EMAs will also include a gambling event record, which will assess gambling expenditure since the last t-EMA completed (e-EMA) (see Primary Outcome).

Intervention content:
Participants will select from a comprehensive list of cognitive and behavioural strategies to limit or reduce their gambling behaviours. Each option contains a strategy name (e.g., social support) and implementation guidance (e.g., talking to someone about gambling). Each strategy is categorised into a higher-order grouping, which we refer to as a strategy group (n=25). Each strategy group contains between four and six strategies, each with detailed implementation guidance (120 strategies in total). Strategy groups are organised into ten higher-order Behaviour Change Technique (BCT) categories: avoidance, rewards, substitution activities and social support, and categories of BCTs identified in the gambling literature (including maintaining momentum, staying in control while gambling, urge management, financial management, and managing emotions).

The action planning component prompts participants to develop personally tailored action plans that respond to immediate threats to adhering to gambling limits. Participants allocated to the intervention condition receive a list of tailored strategy groups (6 to 16 groups) based on the results of their EMA. Participants can select one strategy group, and then the app provides a list of all relevant individual strategies from which participants can select. Upon selection, the app provides a detailed description of methods for implementation (drawn from lived experience research – see consumer involvement section) and offer strategy-specific prompts for the personalisation of the strategy. Once participants are provided with all information and prompted to consider specific details, they are asked to record their action plan.

The coping planning component involves the development of a personally tailored coping plan in response to a proximal implementation barrier. Participants are prompted to identify the main barrier right now to action plan implementation by selecting one of seven categories of barriers: thoughts, emotions, motivation, situation, self-belief, financial, and social barriers. Participants are prompted to describe the selected barrier and to detail how that barrier can get in the way of their action plan. The app then prompts participants to identify what they can do right now to overcome the barrier and get back on track with the plan.

Once the plan is saved, a commitment and self-efficacy activity follows to facilitate engagement and throughput of the strategy. This involves focusing on character strengths and mental rehearsal. Prompts are provided for consideration of character strengths and imagining themselves implementing their plans. Once completed, the app provides an encouraging message. The total time to complete the control condition is approximately 5 minutes, depending on the level of detail provided by the participant.

Intervention options:
Each set of t-EMA responses will be evaluated to determine participant eligibility for intervention delivery according to a set of pre-determined decision rules. In total, 17 t-EMA items (measuring strength of intention, goal self-efficacy, urge self-efficacy, and the presence of a high-risk situation) are used to ascertain whether an individual is eligible to receive an intervention. In this app, each EMA item will be linked with multiple strategy groups (e.g., goal self-efficacy item is linked with 12 strategy groups that incorporate strategies to improve goal confidence). Hence, participants who exceed the cut-point for intervention delivery at each t-EMA will be eligible to receive any of the corresponding strategy groups.

Participants who do not exceed the cut-point for the relevant t-EMA items will not be eligible for any intervention activities. These participants will receive a short encouraging message and their interaction with the app will end.

Importantly, participants who exceed the cut-point for intervention delivery at each t-EMA will
be micro-randomised to one of two conditions: (1) control condition (in which participants will select one behaviour change strategy category relevant to their situation and the app closes with an encouraging message) or (2) an intervention condition. The micro-randomisation procedure will involve a 50% chance of receiving the no intervention control condition and a 50% chance of receiving the intervention condition.

In the intervention condition, participants will select one behaviour change strategy that is relevant to their current situation. Following selection of a strategy participants select a pre-defined action that they are willing to take in the present moment. Participants are then prompted to form an action plan, identify barriers to plan implementation, and form a coping plan. At the end of each intervention activity, participants are asked to identify a personal strength and to describe how this strength can support implementation intentions. Together these components are expected to take around 5 minutes to complete. The intervention concludes with mental rehearsal aimed at strengthening commitment to action and coping plans.

Importantly, Gambling Habit Hacker includes a “provide nothing” option in situations in which the participant is unreceptive, support is not required, or the provision of support may be unsafe, inconvenient, or unethical. Specifically, support will not be offered if the push notification prompting EMA completion is ignored or they press the “snooze” function indicating that are currently unable to complete the EMA (i.e., they are not receptive). Individuals will be allowed two hours to complete an EMA to preserve the momentary nature of the intervention while accommodating the potential for possible unavailability (e.g., driving, working) of the participant at the initial notification time.

Notably, the micro-randomised trial will be conducted over a 28-day period. During this time, intervention activities will only be available in response to the push notification (“push” intervention). These notifications will not be delivered during the six-month follow-up period, but the intervention content will be available to participants “on-demand” during this time (tailored “pull” intervention). During this period of time, participants will be able to access the same tailored intervention activities via a participant-initiated t-EMA.

Intervention code [1]

Behaviour

Comparator / control treatment

As outlined in the Intervention section, participants who exceed the cut-point for an intervention at each t-EMA according to the decision rules will be micro-randomised to one of two conditions, including: (1) a control condition or (2) an intervention condition.

The control condition is the comparator group in the micro-randomised trial (MRT). Participants allocated to the control condition will receive a list of all 25 strategy groups (names only), with no implementation guidance. Once participants select one strategy group name, the app provides an encouraging message. The total time to complete the control condition is approximately 1 minute to read and select a strategy group.

Control group

Active

Outcomes

Primary outcome [1]

For the MRT, the primary proximal outcome is goal attainment (operationalised as a binary outcome, with success defined as actual expenditure being no greater than 10% higher than planned expenditure limits). Actual gambling expenditure, which is measured at each subsequent t-EMA, is measured using a single item similar to that employed in previous gambling EMA research: ‘Since the last time you checked in, how much have you spent in $ gambling? Record 0 if you haven’t gambled’. Planned gambling expenditure is measured using a Timeline Follow-Forward at the pre-intervention evaluation.

Timepoint [1]

For the MRT the primary proximal outcome ‘actual expenditure’ is measured at each subsequent t-EMA. t-EMA assessments are protocol-initiated via push notifications three times a day for 28 days post-intervention commencement. Planned gambling expenditure is measured at pre-intervention evaluation.

Primary outcome [2]

For the within-group follow up evaluation, the primary outcome is gambling expenditure, which is measured using a TimeLine Follow-Back at the pre-intervention evaluation, e-EMA data at the post-intervention evaluation, and single items at the six-month follow-up evaluation.

Timepoint [2]

For the within-group follow-up evaluation, gambling expenditure is measured at pre-intervention, post-intervention, and 6-month follow-up evaluations.

Secondary outcome [1]

For the MRT, a secondary proximal outcome is strength of intention (to adhere to gambling goals), measured by a single item "When thinking about the $$ goal you set on your calendar for today… Right now, I intend to meet my goal." This item was adapted for the gambling context based on the principles of the HAPA approach and using items developed to measure strength of intention in other health-related contexts.

Timepoint [1]

For the MRT, strength of intention is measured at each subsequent t-EMA. t-EMA assessments are protocol-initiated via push notifications three times a day for 28 days post-intervention commencement.

Secondary outcome [2]

For the MRT, a secondary proximal outcome is goal self efficacy (confidence to stick to gambling expenditure limits), measured by a single item, "When thinking about the $$ goal you set on your calendar for today… Right now, I am confident that I can stick to my goal". This item was adapted for the gambling context based on the principles of the HAPA approach and using items developed to measure strength of intention in other health-related contexts.

Timepoint [2]

For the MRT, goal self-efficacy is measured at each subsequent t-EMA. t-EMA assessments are protocol-initiated via push notifications three times a day for 28 days post-intervention commencement.

Secondary outcome [3]

For the MRT, a secondary proximal outcome is urge self-efficacy (focused on confidence to stick to gambling limits despite an urge to gamble). This variable is measured with a single item from the Gambling Urge Scale.

Timepoint [3]

For the MRT, urge self-efficacy is measured at each subsequent t-EMA. t-EMA assessments are protocol-initiated via push notifications three times a day for 28 days post-intervention commencement.

Secondary outcome [4]

For the within-group follow-up evaluation, a secondary outcome is gambling symptom severity, which is measured via the Gambling Symptom Assessment Scale.

Timepoint [4]

For the within-group follow-up evaluation, gambling symptom severity is measured at pre-intervention, post-intervention, and 6-month follow-up evaluations.

Secondary outcome [5]

For the within-group follow-up evaluation, a secondary outcome is gambling frequency, which is measured using a TimeLine Follow-Back at the pre-intervention evaluation, e-EMA data at the post-intervention evaluation, and single items at the six-month follow-up evaluation.

Timepoint [5]

For the within-group follow-up evaluation, gambling frequency is measured at pre-intervention, post-intervention, and 6-month follow-up evaluations.

Secondary outcome [6]

For the within-group follow-up evaluation, a secondary outcome is psychological distress, which is measured by the Kessler 6 Psychological Distress Scale.

Timepoint [6]

For the within-group follow-up evaluation, psychological distress is measured at pre-intervention, post-intervention, and 6-month follow-up evaluations.

Secondary outcome [7]

For the within-group follow-up evaluation, a secondary outcome is personal wellbeing, which is measured by the Personal Wellbeing Index.

Timepoint [7]

For the within-group follow-up evaluation, personal wellbeing is measured at pre-intervention, post-intervention, and 6-month follow-up evaluations.

Secondary outcome [8]

For the within-group follow-up evaluation, situational confidence is measured using the Brief Situational Confidence Questionnaire.

Timepoint [8]

For the within-group follow-up evaluation, situational confidence is measured at pre-intervention, post-intervention, and 6-month follow-up evaluations.

Secondary outcome [9]

For the within-group follow-up evaluation, planning propensity is measured using an adapted action control questionnaire.

Timepoint [9]

For the within-group follow-up evaluation, planning propensity is measured at pre-intervention, post-intervention, and 6-month follow-up evaluations.

Eligibility

Key inclusion criteria

Eligibility criteria will include:
(1) current Australian or New Zealand residence;
(2) 18 years of age or older;
(3) installation of the app from an internet-enabled smartphone;
(4) willingness to receive notifications from the app;
(5) fluency in English language; and
(6) seeking support for one’s own gambling

Minimum age

18 Years

Maximum age

No limit

Sex

Both males and females

Can healthy volunteers participate?

Key exclusion criteria

Consistent with a pragmatic design, this program will be available to any interested gambler, regardless of the level of gambling symptom severity or whether they are seeking other forms of support or treatment.

Study design

Purpose of the study

Treatment

Allocation to intervention

Randomised controlled trial

Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)

Treatment condition allocation procedures will be conducted via the app's pre-specified decision rules without the involvement from any members of the research team. As such, the allocation procedure will be concealed.

Methods used to generate the sequence in which subjects will be randomised (sequence generation)

This study will be a 28-day micro-randomised trial. This will involve randomisation into a control condition or an intervention condition at each t-EMA over the 28-day trial. Micro-randomisation will occur automatically via the app, and because intervention delivery is dependent on participants’ responses to the t-EMAs, participants will not be assigned to the same single intervention condition for the duration of the trial.

Masking / blinding

Blinded (masking used)

Who is / are masked / blinded?

The people administering the treatment/s
The people assessing the outcomes

Intervention assignment

Other

Other design features

Micro-randomised trial (MRT). Each participant will be randomised to an intervention condition or a control condition at each decision point across a 28-day period.

Phase

Not Applicable

Type of endpoint/s

Efficacy

Statistical methods / analysis

To assess the research questions, we will use the method of generalised estimating equations (GEE), with appropriate link function for the outcome of interest (e.g., logit, identity). Whilst we intend to use an exchangeable working correlational structure for analyses, we will consider alternative correlational structures based on the observed within person correlation pattern over the course of the study (e.g., independent or autoregressive). For all MRT analyses, we will regress the (lagged) outcome of interest (e.g., adherence to expenditure limit at Time t+1) on to a variable denoting the treatment received (i.e., Intervention vs Control) at Time t, as well as covariates (including unbalanced time). The primary analyses will explore the effect of Intervention vs Control on the probability of adherence to expenditure limits at the subsequent episode. The identification of the conditions under which the interventions are most beneficial and how the effect of the interventions change over the course of the MRT will be examined by specifying interaction terms between the intervention variable and interaction variables of interest (e.g., strength of intention, time). To explore the longer-term outcomes of the intervention (within-group follow-up evaluation), distal outcomes will also be assessed using GEE by regressing the outcome of interest (e.g., gambling expenditure) on to a variable denoting time (i.e., pre-intervention, post-intervention, six-month follow-up) and covariates. Where appropriate, we will address missingness using multiple imputation with appropriate accounting for the multilevel nature of the data (e.g., see multilevel multiple imputation).

Using within-group data collected at pre-intervention, post-intervention and 6-month follow-up evaluations, we will consider the clinical significance of any effect in the trial, including: (1) effect sizes (standardised beta); (2) clinically significant change, whereby each participant’s status will be defined as recovered, improved, unchanged, or deteriorated, based on the Gambling Symptom Severity Scale (G-SAS) and Kessler Psychological Distress Scale (K6); and (3) an expenditure goal achievement scale, in which the concordance between actual and intended gambling behaviour (expenditure and frequency) is calculated.

Recruitment

Recruitment status

Recruiting

Date of first participant enrolment

Anticipated

25/04/2022

Actual

12/04/2022

Date of last participant enrolment

Anticipated

18/08/2023

Actual

Date of last data collection

Anticipated

15/03/2024

Actual

Sample size

Target

200

Accrual to date

210

Final

Recruitment in Australia

Recruitment state(s)

ACT,NSW,NT,QLD,SA,TAS,WA,VIC

Recruitment outside Australia

Country [1]

New Zealand

State/province [1]

Funding & Sponsors

Funding source category [1]

Government body

Name [1]

New South Wales Office of Responsible Gambling

Address [1]

Responsible Gambling Fund, PO Box 7060, Sydney, NSW 2001

Country [1]

Australia

Primary sponsor type

University

Name

Deakin University

Address

221 Burwood Highway, Burwood, 3125 Victoria

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Deakin University Human Research Ethics Committee

Ethics committee address [1]

221 Burwood Highway, Burwood, 3125 Victoria

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

28/08/2020

Approval date [1]

08/10/2020

Ethics approval number [1]

2020-304

Summary

Brief summary

The aim of this cutting-edge micro-randomised trial is to evaluate the effectiveness of a new Just-In-Time Adaptive Intervention delivered via a smartphone app for people who want to adhere to their gambling expenditure limits. This implementation intention app intervention will use in-the-moment information about personal gambling intentions and corresponding barriers (e.g., strong cravings) to promote adherence to gambling intentions in real-time. Participants will complete very brief real-time assessments three times per day via the app, which will be used to determine their eligibility for a real-time intervention. Participants who are eligible to receive an intervention at each assessment time point will be micro-randomised to one of two conditions: an intervention condition or a control condition. Participants will also complete pre-intervention, post-intervention, and 6-month follow-up evaluations to determine change over time. In so doing, this trial will evaluate the efficacy of the app intervention and when and for whom the intervention is effective.

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

Prof Nicki Dowling

Address

Deakin University, 221 Burwood Highway, Burwood, 3125 Victoria

Country

Australia

Phone

+61 3 9244 5610

Fax

nicki.dowling@deakin.edu.au

Contact person for public queries

Name

Simone Rodda

Address

Deakin University, 221 Burwood Highway, Burwood, 3125 Victoria

Country

Australia

Phone

+61 3 9244 5610

Fax

simone.rodda1@deakin.edu.au

Contact person for scientific queries

Name

Simone Rodda

Address

Deakin University, 221 Burwood Highway, Burwood, 3125 Victoria

Country

Australia

Phone

+61 3 9244 5610

Fax

simone.rodda1@deakin.edu.au

Data sharing statement

Will individual participant data (IPD) for this trial be available (including data dictionaries)?

No/undecided IPD sharing reason/comment

What supporting documents are/will be available?

Doc. No.	Type	Citation	Link	Email	Other Details	Attachment
15084	Study protocol	Rodda, S. N., Bagot, K. L., Merkouris, S. S., Youssef, G., Lubman, D. I., Thomas, A. C., & Dowling, N. A. (2022). Smartphone App Delivery of a Just-In-Time Adaptive Intervention for Adult Gamblers (Gambling Habit Hacker): Protocol for a Microrandomized Trial. JMIR Research Protocols, 11(7), e38919.	https://www.researchprotocols.org/2022/7/e38919		See study protocol publication above
15085	Clinical study report				TBA

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